This present invention relates to a method for supporting distribution means, such as a pipeline or aqueduct. More particularly, the present invention relates to a homeostatic method for supporting distribution means that accommodates temperature-induced expansion or contraction of the distribution means, resists unexpected, infrequent shocks such as might be encountered during an earthquake or similar disaster, and provides effective thermal isolation of the distribution means from the surface on which the structure rests.
Conventional methods for supporting distribution means such as pipelines frequently are designed to use essentially rigid structures, i.e., the structures do not yield appreciably on the application of an external force. When an external force is applied to such a rigid structure, a variety of tensile, compressive and bending forces may be created within the structure. If the external force is sufficiently high, the method for supporting the distribution means may fail, resulting in rupture of the pipeline.
Release of the substances contained in a pipeline or other distribution means may result in disruption of the supply of such substances to users, for example, the supply of water to a municipal water system, fuel to a power plant, or feedstock chemicals to a manufacturing plant. Release of these substances also may result in other adverse effects, such as flooding, exposure of persons to thermally or physiologically harmful substances, or environmental contamination. To reduce the risk of such occurrences, existing methods for supporting distribution means frequently call for overdesign of at least some portions of these rigid supporting structures.
In addition, conventional methods for supporting distribution means generally are ineffective in minimizing undesirable thermal transfer from the distribution means to the supporting structure when the temperature of the material contained in the distribution means varies substantially from the ambient temperature. For example, oil being transported by pipeline through extremely cold regions must be kept warm to maintain flow in the pipeline; however, heat transferred from the pipeline to its supporting structure may in turn be transferred to the ground supporting the structure, resulting in undesirable melting of frozen matter adjacent the structure, including permafrost soil. Melting of the permafrost may lead to instability of the supporting structure in addition to adverse environmental consequences. In addition, melting of snow and ice produces water that accelerates corrosion of metal parts of the distribution means and its supporting structure.
The present invention provides a method for supporting a pipeline or other distribution means on a structure whose elements are in or tending toward a relatively stable state of equilibrium. "Homeostasis" is defined as "a relatively stable state of equilibrium or a tendency toward such a state between the different but interdependent elements or groups of elements of an organism or group" (Webster's New Collegiate Dictionary, G.&C. Merriam Co., 1976). Hence the method of the present invention may be referred to as a homeostatic method.
The present invention provides a method of supporting distribution means that includes arranging laterally spaced apart fixed bearing members on a surface adjacent a path for distribution means and supporting elongated elastic members on a bearing surface of the bearing members at a distance spaced inwardly from the ends of the elastic members. Each elastic member is capable of bending in proportion to the magnitude of a load applied intermediate its ends. Distribution means may be placed in association with the elastic members, each of which supports only the share of the distribution means which is acting directly above it. The method of the present invention establishes an equilibrium state between the bending elastic members and the weight of the distribution means.
Beginning from such an equilibrium state, an additional load applied intermediate the ends of the elastic members causes the midportion of each elastic member to bend from a first equilibrium position an amount proportional to the magnitude of the additional load and assume a second, more downwardly bowed position. The ends of the elastic members slide against the bearing members a distance also proportional to the magnitude of the additional load as the midportion bows downwardly. The movement of the elastic members establishes a new equilibrium state between the bending elastic members and the weight of the distribution means. When the additional load is removed, the midportions unbow, returning to substantially the same positions as their original equilibrium positions. The ends of the elastic members slide a corresponding distance in the opposite direction, also returning to substantially the same positions as their original equilibrium positions. The midportions of the elastic members bend and the ends of the elastic members slide in a similar manner in response to a force applied upwardly against the bottom of the elastic members or to a force applied against any of the bearing supports.
The bending and sliding of the elastic members in response to changes in the load supported by the structure may perform shock and energy absorbing functions when the elastic members engage the bearing surface. The absorbed energy is dissipated primarily in the form of heat generated by the frictional contact between the elastic members and the bearing surfaces. Preferably, the elastic members engage the bearing surface during bending from an external force at a homeostatic, or critical, angle, i.e., an angle within the range of about 25 to about 50 degrees from a vertical axis of support for the structure.
In the method of the present invention, the contact between the elastic members on which the distribution means is supported and the ground-engaging fixed bearing members is minimized, thereby reducing undesirable thermal transfer from the distribution means to the supporting structure and thence to the ground. In addition, the method of the present invention may include providing means for dissipating heat into the air more efficiently than conventional methods, because the heat dissipating means may be attached directly to elements of the supporting structure that are in contact with the distribution means.